The present invention relates to golf balls and, more particularly, a method of coating thin layers on a variety of golf ball components and/or golf equipment.
The modern golf ball may be constructed in virtually an unlimited number of ways. By altering ball construction and composition, manufacturers can vary a wide range of playing characteristics, such as resilience, durability, spin, and xe2x80x9cfeel,xe2x80x9d each of which can be optimized for various playing abilities. The golf ball components, in particular, that many manufacturers continually look to improve are the center or core, intermediate layers, if present, and covers.
One common way in which manufacturers adjust the properties of golf balls is by varying the construction of golf ball intermediate and cover layers. These layers have conventionally been formed by compression or injection molding various polymer materials, such as ionomers and polyurethanes of varying hardness and flexural moduli. Injection and compression molding, however, are not without problems and limitations. Both types of molding have practical limitations on layer thickness. It is difficult and impractical, if not impossible, to compression or injection mold a layer having a thickness of less than about 0.03 inches. It is not difficult to recognize that once layers become very thin uniformity problems arise. Additionally, it is particularly difficult to injection and compression mold layers onto soft golf ball cores because the resulting deformation of the core due to molding temperatures and pressures. Other types of molding, such as casting and reaction injection molding (xe2x80x9cRIMxe2x80x9d) also have limitations. Casting processes generally have excessive waste and RIM mold parts are difficult to position to achieve a uniform layer. There remains a need, therefore, for improved methods for creating very thin, uniform polymer layers on golf balls and golf equipment.
The present invention is directed to a method for coating a golf ball comprising the steps of providing a golf ball component; providing a polymer material; creating a polymer particulate from the polymer material; fluidizing the polymer particulate; and coating the golf ball component with a thin layer of the polymer material by placing the golf ball component within the fluidized particulate.
The golf ball component can be any component normally used in the construction of a golf ball, but is preferably a solid center, a fluid-filled center, an outer core layer,an intermediate layer, a cover layer; an outer cover, or a golf ball.
The polymer material includes vinyl resins; polyolefins; polyurethanes; polyureas; polyamides; acrylic resins; thermoplastics; thermosets; polyphenylene oxide resins; thermoplastic polyesters; polycarbonates; acrylonitriles; butadiene styrenes; polybutylcnes; polyethylenes; and blends of thermoplastic rubbers with polyethylenes; polypropylenes; polyacetals; nylons; polyesters; epoxies; glycidyl polymers; or cellulose esters.
The polymer particulate can be created by a number of grinding methods, including physical grinding, cryo-grinding, dispersion and evaporation, or surfactant foaming. Fluidizing the particulate can further be effectuated by placing the polymer particulate in a reservoir; injecting compressed air into the reservoir; and allowing the air to percolate through the polymer particulate.
The compressed air may flow through a porous diffuser plate positioned below the reservoir and is preferably injected at a pressure of between about 5 psi and about 15 psi, at least at a pressure sufficient to separate the polymer particulate and cause density reduction.
The golf ball component may also be pre-heated prior to placing the component within the fluidized particulate, preferably using an oven, hot-air convection, or infrared heating to a temperature of between about 250xc2x0 F. and about 500xc2x0 F. Additionally, golf ball component to be coated may also be heated, before or after coating. At least one of the golf ball component or polymer particulate may also be charged prior to fluidized coating.
The golf ball component may also be prepared for coating by a variety of cleaning, preparing, and drying steps. Preferably, the coating has a thickness of less than about 0.03 inches, more preferably less than about 0.01 inches, most preferably between about 0.004 inches and about 0.0.1 inches.
The present invention is also directed to a method for coating a golf ball comprising the steps of providing a golf ball component; providing a polymer material; creating a polymer particulate from the polymer material; fluidizing the polymer particulate by injecting air through the polymer particulate; and coating the golf ball component with a thin-layer of the polymer material by placing the golf ball component within the fluidized particulate.
The present invention is further directed to a method for coating a golf ball comprising the steps of providing a golf ball component; providing a polymeric material; creating a polymer particulate from the polymer material; charging at least one of the component or the particulate; fluidizing the particulate; and coating the golf ball component with a thin layer of the polymer material by placing the golf ball component within the fluidized particulate. The step of charging typically includes grounding the component and applying a voltage to the particulate to form a charged cloud of powder. Preferably, the voltage is a negative voltage and ranges from about 10 kV to about 20 kV. In one embodiment, the voltage is applies via a set of electrodes positioned near the diffuser plate. To coat a thin layer, the component is preferably conveyed through the charged cloud of powder and, alternatively, passed through a curing oven in which the powder is heated to its melting temperature to form a uniform layer. Most preferably, the coating formed by electrostatic charging has a thickness of less than about 0.01 inches.